9. Arthur Mitchell AKA: The Trinity Killer (Dexter)
Seeming to be loosely based on the real serial killer, BTK, Arthur Mitchell manages to maintain his dual personalities as a family man and brutal killer for upwards of 30 years. He is dubbed the Trinity Killer because of his penchant for killing in sets of three; Always the same modus operandi. The first victim is always a female whom he drugs, strips and forces into a bathtub with him. He then cuts her femoral artery and holds a mirror in front of her face so he can watch her slowly die while holding her. His second murder is a middle aged mother whom he would convince to jump to her death by threatening her children. The third was always a middle aged man who he would bludgeon to death. All of these victims symbolize various cogs in the wheel that was his tumultuous childhood. John Lithgow plays this undercover monster brilliantly. His ability to slide from sympathetic father figure into an unhinged, brutally ritualistic killer gives this character oodles of dimension. One minute, he is scalding himself in a shower as punishment and the next he is coldly carrying out the murder of an innocent. Lithgow makes it such a believable dichotomy and really recalls the complete lack of control that the real BTK demonstrated. He is that guy over there who you wave to before leaving for work every morning. He is the friendly man in line for coffee or the person sitting in the next pew at church. He could be anyone, and that is downright terrifying.